The Minnesota Transracial Adoption Study examined the IQ test scores of 130 black or interracial children adopted by advantaged white families. The aim of the study was to determine the contribution of environmental and genetic factors to the poor performance of black children on IQ tests as compared to white children. The initial study was published in 1976[1] by Sandra Scarr and Richard A. Weinberg. A follow-up study was published in 1992[2] by Richard Weinberg, Sandra Scarr and Irwin D. Waldman. Another related study investigating social adjustment in a subsample of the adopted black children was published in 1996.[3] The 1992 follow-up study found that "social environment maintains a dominant role in determining the average IQ level of black and interracial children and that both social and genetic variables contribute to individual variations among them."[4]
On measures of cognitive ability (IQ tests) and school performance, black children in the U.S. have performed worse than white children. At the time of the study, the gap in average performance between the two groups of children was approximately one standard deviation, which is equivalent to about 15 IQ points or 4 grade levels at high school graduation. Thus, the average IQ score of black children in the U.S. was approximately 85, compared to the average score of white children of 100. No detectable bias due to test construction or administration had been found, although this does not rule out other biases. The gap is functionally significant, which makes it an important area of study. The Minnesota Transracial Adoption Study tried to answer whether the gap is primarily caused by genetic factors or whether it is primarily caused by environmental and cultural factors.
By examining the cognitive ability and school performance of both black and white children adopted into white families, the study intended to separate genetic factors from rearing conditions as causal influences in the gap. "Trans racial adoption is the human analog of the cross-fostering design, commonly used in animal behavior genetics research.... There is no question that adoption constitutes a massive intervention" (Scarr & Weinberg, 1976, p.726).
Scarr and Weinberg studied black, white, Asian, indigenous American, and mixed-race black/white children adopted by upper-middle-class white families in Minnesota. The average IQ of the adopting parents was more than one standard deviation above the population mean of 100. The biological children of these parents were also tested. The sample of adopted children was selected by eligible parents contacting the researchers for participating following a newsletter call. The geographical origin of the adopted children was not uniform. All except one white adopted child was adopted in-state. Black and interracial children came from twelve states; Asian and indigenous American children came from Minnesota as well as from Korea, Vietnam, Canada and Ecuador.
As Scarr & Weinberg (1976) note, transracial adoption studies only control for family environment, not social environment. For example, children who are socially identified as black may still be subject to racial discrimination despite being raised by white parents. Yet, it was previously known that adoption into upper-middle class white families has a positive influence on the IQ and school performance of white children.
The study showed significant differences in adoption patterns of mixed-race black/white and black adopted children as was noted by Scarr and Weinberg (1976):
It is essential to note, however, that the groups also differed significantly (p < .05) in their placement histories and natural mother's education. Children with two black parents were significantly older at adoption, had been in the adoptive home a shorter time, and had experienced a greater number of preadoption placements. The natural parents of the black/black group also averaged a year less of education than those of the black/white group, which suggests an average difference between the groups in intellectual ability. There were also significant differences between the adoptive families of black/black and black/white children in father's education and mother's IQ.[1]
Results
The children were first tested in 1975 at age 7. In 1985, 196 of the original 265 children were retested at age 17. The data showed mixed adoptees scoring slightly lower than white adoptees with gaps of 3 and 7 points at ages 7 and 17, while black adoptees scored 15 and 17 points below white adoptees at ages 7 and 17.
Adopting parents tested when children were 7 and 17
120
115
—
—
—
Non adopted, with two white biological parents
117
109
3.0
64
69
Adopted, with two white biological parents
112
106
2.8
54
59
Adopted, with one white and one black biological parent
109
99
2.2
40
53
Adopted, with Asian or indigenous American parents
100
96
—
—
—
Adopted, with two black biological parents
97
89
2.1
36
42
The adopting parents of 12 of the interracial children wrongly believed that their adopted children had two black parents. The average IQ of these 12 children was not significantly different from the scores of the 56 interracial children correctly classified by their adoptive parents as having one black and one white parent.[1]
Some have suggested that differing pre-adoption experiences, including age at adoption, explain the racial patterns in the results. Lee (2009) argues against this interpretation, saying that there is no evidence from other studies that variables such as age at adoption exert an effect on IQ lasting until late adolescence. In the Minnesota study, the proportion of IQ variance associated with pre-adoption variables declined from .32 to .13 between ages 7 and 17.[5]
The average difference in IQ scores between the testing at age 7 and testing at age 17, seen in all groups, may be due to the use of different IQ tests.[2] The original study used Stanford–Binet Form L-M, WISC or WAIS tests, depending on age, while the follow-up used WISC-R or WAIS-R. Weinberg, Scarr and Waldman describe the effect of this change in test:
Declines in IQ scores have been documented when individuals are retested on a revised form of an original measure, as well as when a test used at a first administration was normed earlier than a test used at a subsequent administration (see Flynn, 1984, for a review). For example, the decline in Full-Scale IQ score from the WAIS to the WAIS-R averaged 6.8 points across a number of studies (reviewed by Sattler, 1988) and was 7.5 points in a sample of 72 35- to 44-year-olds tested as part of the standardization of the WAIS-R (Wechsler, 1981). This is precisely the test combination used for adoptive parents in our study.
Everyone involved in this debate is well-aware that such comparisons must be corrected for the Flynn effect: Mean scores on all standard IQ tests seem to rise steadily at about 0.3 points per year. In the Minnesota study, where the tests used in the follow-up were generally not the same as those that had been given the first time, these corrections are complex and must be made on an individual basis. Until they have been made–Waldman et al. reported that they are in progress–raw figures like those above are relatively meaningless.[6]
The data, corrected for the Flynn effect, was published in 2000 by John Loehlin in the Handbook of Intelligence.[7] The data showed mixed adoptees scoring lower than white adoptees with gaps of 6.1 and 8.3 points at ages 7 and 17, while black adoptees scored 20.1 and 17.8 points below white adoptees at ages 7 and 17.
Children's background
Number of Children
Age 7 Corrected IQ
Age 17 Corrected IQ
Non adopted, with two white biological parents
101
110.5
105.5
Adopted, with two white biological parents
16
111.5
101.5
Adopted, with one white and one black biological parent
55
105.4
93.2
Adopted, Asian or indigenous American parents
12
96.1
91.2
Adopted, with two black biological parents
21
91.4
83.7
The analysis of structured interviews at age 7 and 17 reported by (DeBerry, Scarr & Weinberg 1996) found that about half of the studied black adopted children had adjustment difficulties. They had difficulties becoming competent in both European and African-American reference group orientation but had stronger affinity with the European than with the African-American group. Stronger identification with one or the other group predicted better adjustment.[3]
Interpretations
Scarr & Weinberg (1976) interpreted the results from age 7 suggesting that racial group differences in IQ are inconclusive because of confounding in the study. They noted, however, that the study indicated that cross-racial adoption had a positive effect on black-adopted children. In support of this interpretation, they drew special attention to the finding that the average IQ of "socially classified" black children was greater than that of the U.S. white mean. The follow-up data were collected in 1986, and Weinberg et al. published their findings in 1992; they interpreted their results as still supporting the original conclusions.
Both Levin[8] and Lynn[9] argued that the data support a hereditarian alternative - that the mean IQ scores and school achievement of each group reflected their degree of Sub-Saharan African ancestry. For all measures, the children with two black parents scored lower than the children with one black and white parent, who in turn scored lower than the adopted children with two white parents. Both omitted discussion of Asian adoptees.
Waldman, Weinberg, and Scarr[10] responded to Levin[8] and Lynn.[9] They noted that the data taken of adoption placement effects can explain the observed differences but that they cannot make that claim firmly because the pre-adoption factors confounded racial ancestry, preventing an unambiguous interpretation of the results. They also note that Asian data fit that hypothesis while being omitted by both Levin and Lynn. They argued that, "contrary to Levin's and Lynn's assertions, results from the Minnesota Transracial Adoption Study provide little or no conclusive evidence for genetic influences underlying racial differences in intelligence and achievement, " and noted that, "We think that it is exceedingly implausible that these differences are either entirely genetically based or entirely environmentally based. The true causes of racial-group differences in IQ, or in any other characteristic, are likely to be too complex to be captured by locating them on a single hereditarianism-environmentalism dimension."[10]
In a 1998 article, Scarr wrote, "The test performance of the Black/Black adoptees [in the study] was not different from that of ordinary Black children reared by their own families in the same area of the country. My colleagues and I reported the data accurately and as fully as possible, and then tried to make the results palatable to environmentally committed colleagues. In retrospect, this was a mistake. The results of the transracial adoption study can be used to support either a genetic difference hypothesis or an environmental difference one (because the children have visible African ancestry). We should have been agnostic on the conclusions . . ."[11] Later opinions supported Scarr's reassessment. For example, one group of authors wrote, "Generally, scholars in the field of intelligence see the evidence from this study . . . as consistent with both environmental and genetic hypotheses for the cause of Group IQ score differences . . ."[12]
Loehlin (2000) reiterates the confounding problems of the study and notes that both genetic and environmental interpretations are possible. He further offers another possible explanation of the results, namely unequal prenatal factors: "[O]ne possibility lies in the prenatal environment provided by Black and White biological mothers. The Black-Black group, of course, all had Black mothers. In the Black-White group, virtually all of the birth mothers were White (66 of 68). Willerman and his colleagues found that in interracial couples it made a difference whether the mother was Black or White: The children obtained higher IQs if she was White. They suspected that this difference was due to postnatal environment, but it could, of course, have been in the prenatal one."[7]
A paper from Drew Thomas (2016) found that once corrected for the Flynn effect and attrition in the low IQ white adoptees, the MTRA data showed mixed adoptees scoring slightly lower than white adoptees with a gap of 2.5 points at age 7 and 3.5 at age 17, while black adoptees scored 12.2 and 11.7 points below white adoptees at ages 7 and 17; however, with confidence intervals on the order of ±3 points, these should be taken as rough estimates. Thomas believes that the black-white gap may be explained by differences in pre-adoption environment and age at adoption.[13]
Arthur Robert Jensen was an American psychologist and writer. He was a professor of educational psychology at the University of California, Berkeley. Jensen was known for his work in psychometrics and differential psychology, the study of how and why individuals differ behaviorally from one another.
An intelligence quotient (IQ) is a total score derived from a set of standardised tests or subtests designed to assess human intelligence. The abbreviation "IQ" was coined by the psychologist William Stern for the German term Intelligenzquotient, his term for a scoring method for intelligence tests at University of Breslau he advocated in a 1912 book.
Discussions of race and intelligence – specifically regarding claims of differences in intelligence along racial lines – have appeared in both popular science and academic research since the modern concept of race was first introduced. With the inception of IQ testing in the early 20th century, differences in average test performance between racial groups were observed, though these differences have fluctuated and in many cases steadily decreased over time. Complicating the issue, modern science has concluded that race is a socially constructed phenomenon rather than a biological reality, and there exist various conflicting definitions of intelligence. In particular, the validity of IQ testing as a metric for human intelligence is disputed. Today, the scientific consensus is that genetics does not explain differences in IQ test performance between groups, and that observed differences are environmental in origin.
The Bell Curve: Intelligence and Class Structure in American Life is a 1994 book by psychologist Richard J. Herrnstein and political scientist Charles Murray, in which the authors argue that human intelligence is substantially influenced by both inherited and environmental factors and that it is a better predictor of many personal outcomes, including financial income, job performance, birth out of wedlock, and involvement in crime than are an individual's parental socioeconomic status. They also argue that those with high intelligence, the "cognitive elite", are becoming separated from those of average and below-average intelligence, and that this separation is a source of social division within the United States.
Adoption is a process whereby a person assumes the parenting of another, usually a child, from that person's biological or legal parent or parents. Legal adoptions permanently transfer all rights and responsibilities, along with filiation, from the biological parents to the adoptive parents.
Transracial may refer to:
Joseph M. Horn(born August 9, 1940) is an American psychologist and geneticist known for his work on adoption studies.
Sandra Wood Scarr was an American psychologist and writer. She was the first female full professor in psychology in the history of Yale University. She established core resources for the study of development, including the Minnesota Transracial Adoption Study and the Minnesota Adolescent Adoption Study. She served as president of multiple societies including the Association for Psychological Science and was honored with multiple awards including the James McKeen Cattell Fellow Award. She was also active in the development of commercial childcare. Her work with twins in the 1960s revealed strong genetic influences on intellectual development. One of her key findings was that this differed with race and socioeconomic status (SES), with poor and non-white children showing less genetic influence on their IQ and more environmental influence. She demonstrated a successful intervention in premature infants, showing that stimulation improved their health and developmental outcomes.
In the United States, adoption is the process of creating a legal parent–child relationship between a child and a parent who was not automatically recognized as the child's parent at birth.
Interracial adoption refers to the act of placing a child of one racial or ethnic group with adoptive parents of another racial or ethnic group.
Research on the heritability of IQ inquires into the degree of variation in IQ within a population that is due to genetic variation between individuals in that population. There has been significant controversy in the academic community about the heritability of IQ since research on the issue began in the late nineteenth century. Intelligence in the normal range is a polygenic trait, meaning that it is influenced by more than one gene, and in the case of intelligence at least 500 genes. Further, explaining the similarity in IQ of closely related persons requires careful study because environmental factors may be correlated with genetic factors.
Race Differences in Intelligence: An Evolutionary Analysis is a 2006 book by controversial race and intelligence writer Richard Lynn. The book reviews selected literature on IQ testing and argues that genetic racial differences exist, with a discussion of the causes and consequences. Reviews of the book fault the selection of data used, the methodology, and the conclusions drawn from the data, resulting in criticism that it is "the sort of book that gives IQ testing a bad name."
"Mainstream Science on Intelligence" was a public statement issued by a group of researchers led by psychologist Linda Gottfredson. It was published originally in The Wall Street Journal on December 13, 1994, as a response to criticism of the book The Bell Curve by Richard Herrnstein and Charles Murray, which appeared earlier the same year. The statement defended Herrnstein and Murray's controversial claims about race and intelligence, including the claim that average intelligence quotient (IQ) differences between racial and ethnic groups may be at least partly genetic in origin. This view is now considered discredited by mainstream science.
The history of the race and intelligence controversy concerns the historical development of a debate about possible explanations of group differences encountered in the study of race and intelligence. Since the beginning of IQ testing around the time of World War I, there have been observed differences between the average scores of different population groups, and there have been debates over whether this is mainly due to environmental and cultural factors, or mainly due to some as yet undiscovered genetic factor, or whether such a dichotomy between environmental and genetic factors is the appropriate framing of the debate. Today, the scientific consensus is that genetics does not explain differences in IQ test performance between racial groups.
The Eyferth study, conducted by German psychologist Klaus Eyferth, examined the IQs of white and racially-mixed children raised by single mothers in post-World War II West Germany. The mothers of the children studied were white German women, while their fathers were white and black members of the US occupation forces. In contrast to results obtained in many American studies, the average IQs of the children studied were roughly similar across racial groups, making the study an oft-cited piece of evidence in the debate about race and intelligence.
"How Much Can We Boost IQ and Achievement?" is a 1969 article by Arthur Jensen published in the Harvard Educational Review. It is among the most controversial in American psychology, and was largely responsible for initiating the current debate over race and intelligence.
Adoption studies typically compare pairs of persons, e.g., adopted child and adoptive mother or adopted child and biological mother, to assess genetic and environmental influences on behavior. These studies are one of the classic research methods of behavioral genetics. The method is used alongside twin studies to identify the roles of genetics and environmental variables that impact intelligence, and behavioral disorders.
Transracial is a label used by people who identify as a different race than the one they were born into. They may adjust their appearance to make themselves look more like that race, and may participate in activities associated with that race. Use of the word transracial to describe this is new and has been criticized, because the word was historically used to describe a person raised by adoptive parents of a different ethnic or racial background, such as a Black child adopted and raised by a white couple.
Jensenism is a term coined by New York Times writer Lee Edson. Named after educational psychologist Arthur Jensen, it was originally defined as "the theory that IQ is largely determined by the genes". The term was coined after Jensen published the article "How Much Can We Boost IQ and Scholastic Achievement?" in the Harvard Educational Review in 1969. It has since been included in several dictionaries.
In behavioral genetics, the Scarr–Rowe effect, also known as the Scarr–Rowe hypothesis, refers to the proposed moderating effect of low socioeconomic status on the heritability of children's IQ. According to this hypothesis, lower socioeconomic status and greater exposure to social disadvantage during childhood leads to a decrease in the heritability of IQ, as compared to children raised in more advantaged environments. It is considered an example of gene–environment interaction. This hypothesized effect was first proposed by Sandra Scarr, who found support for it in a 1971 study of twins in Philadelphia, and these results were replicated by David C. Rowe in 1999. Since then, similar results have been replicated numerous times, though not all replication studies have yielded positive results. A 2015 meta-analysis found that the effect was predominant in the United States while less evident in societies with robust child welfare systems.
References
1 2 3 Scarr, S.; Weinberg, R. A. (1976). "IQ test performance of black children adopted by White families". American Psychologist. 31 (10): 726–739. doi:10.1037/0003-066x.31.10.726.
1 2 Weinberg, R. A.; Scarr, S.; Waldman, I. D. (1992). "The Minnesota Transracial Adoption Study: A follow-up of IQ test performance at adolescence". Intelligence. 16: 117–135. doi:10.1016/0160-2896(92)90028-p.
1 2 DeBerry, K. M.; Scarr, S.; Weinberg, R. A. (1996). "Family Racial Socialization and Ecological Competence: Longitudinal Assessments of African-American Transracial Adoptees". Child Development. 67 (5): 2375–2399. doi:10.1111/j.1467-8624.1996.tb01863.x.
↑ Weinberg, R. A.; Scarr, S.; Waldman, I. D. (1992). "The Minnesota Transracial Adoption Study: A follow-up of IQ test performance at adolescence". Intelligence. 16: 118. doi:10.1016/0160-2896(92)90028-p.
↑ Lee, J.J. (2009). Review of Intelligence And How to Get It: Why Schools And Cultures Count, R.E. Nisbett, Norton, New York, NY (2009). ISBN978-0-393-06505-3. Personality and Individual Differences 48, 247-255.
1 2 Loehlin, John (2000). "Group Differences in Intelligence". In Robert J. Sternberg (ed.). The Handbook of Intelligence. Cambridge University Press.; Table 9.3, p 185.
1 2 Lynn, R (1994). "Some reinterpretations of the Minnesota Transracial Adoption Study". Intelligence. 19: 21–27. doi:10.1016/0160-2896(94)90050-7.
1 2 Waldman, I. D.; Weinberg, R. A.; Scarr, S. (1994). "Racial-group differences in IQ in the Minnesota Transracial Adoption Study: A reply to Levin and Lynn". Intelligence. 19: 29–44. doi:10.1016/0160-2896(94)90051-5.
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